#!/usr/bin/env node

const { Readable } = require('stream');

class MyReadable extends Readable {
  constructor() {
    super();
    this.#c = 'a'.charCodeAt(0);
  }
  _read() {
    this.push(String.fromCharCode(this.#c++));
    if (this.#c > 'z'.charCodeAt(0)) {
      this.push(null);
    };
  }
  #c
}
const mr = new MyReadable();

mr.pipe(process.stdout);